Very high frequency electric discharge device



y 1956 G. DIEMER 2,754,447

VERY HIGH FREQUENCY ELECTRIC DISCHARGE DEVICE Filed Nov. 19, 1952 I I IINVENTOR. Grsnvws .DLEMER United States Patent VERY HIGH FREQUENCYELECTRIC DISCHARGE DEVICE Gesinus Diemer, Eindhoven, Netherlands,assignor to Hartford National Bank and Trust Company, Hartford, Conn.,as trustee Application November 19, 1952, Serial No. 321,469

Claims priority, application Netherlands December 6, 1951 '2 Claims.(Cl. 3154) The invention relates to devices of the kind comprising anelectric discharge tube which is suitable for use at very highfrequencies and, more particularly, to devices and tubes operating onthe dynatron principle, in which the tubes are connected to concentricLecher systems For very high frequencies (250 to 1000 mc./s.) use isfrequently made of tubes of special construction, for example, tubescomprising sealed-in discs. These constructions, however, dilferconsiderably from those of conventional tubes.

According to the invention it is now possible to manufacture tubes, inprinciple, of the conventional construction, particularly suitable forconnection to concentric Lecher systems and operating satisfactorily upto 1000 mc./ s. According to the invention this may be obtained, if witha device comprising an electric discharge tube for very highfrequencies, having an electrode system including an electron gun whichproduces a ribbon-shaped beam directed to a secondarily emissiveauxiliary cathode, the secondary electrons of which are collected by ananode, the auxiliary cathode has a U-shaped crosssectional area, theclosed side of which faces the electron gun, the auxiliary cathode beingsupported by a central pin, which is secured between the limbs of the Uand is taken directly through the bottom of the tube to the outside, thecylindrical anode surrounding coaxially the auxiliary cathode and beingsecured to a plurality of studs sealed in a circle around about thecentral pin of the auxiliary cathode, to which studs are also securedinside and outside the tube cylindrical screens forming a prolongationof the anode to a concentric Lecher system, the central conductor ofwhich is in line with the central pin of the auxiliary cathode.

This arrangement may provide the same advantages as tubes havingsealed-in discs, without the need of sealing such large disc-shapedmembers in glass, since the tube construction according to the inventionmay, in principle, be identical with the conventional construction oftubes having a glass bottom, more particularly, of small tubes, forexample, having a bulb diameter of less than 25 mms.

Owing to the central arrangement of the pin of the auxiliary cathode,which is coaxially surrounded by a screen of the anode, also outside thetube, a concentric Lecher system can be secured to the pin and thescreen in a very simple manner. Moreover, parasitic radiation isavoided, since the auxiliary cathode itself is also completelysurrounded by the anode, so that no radiation damping occurs and a highalternating voltage is permissible between the anode and the auxiliarycathode. Moreover, all supply pins are located at one end of the tube.Since the screens associated with the anode extend inside and outsidethe tube as far as the proximity of the tube bottom, substantially thesame effect is obtained as with an uninterrupted screen sealed in thebottom of the tube.

In order that the invention may be readily carried into effect, it willnow be described in detail with reference to the accompanying drawing,in which Fig. 1 shows a tube for use in the device according to' theinvention,

Fig. 2 is a cross sectional view of the electrode system of the tubeshown in Fig. 1 and Fig. 3 is a bottom view of the tube bottom.

Referring to Fig. 1, reference numeral 1 designates the' bulb of thetube, which may be secured to a concentric Lecher system 2. The tubecomprises an electron gun 3, an anode 4 and screens 5 and 6, whichconstitute a prolongation of the anode 4, whereas the screen 7 is to beregarded as a prolongation of the screen 6 and hence, of the anodecylinder outside the tube. The screen 5 is closed at the upper end by a'metal'p'late' 8, in which: is secured the cesium pill to activate thesecondarily emissive auxiliary cathode 9, housed inside the anode 4-(Fig. 2). shaped strip of copper plated nickel, the limbs of WhlChz aresoldered to the central pin 10. The limbs also serve: as cooling membersand the closed side of the. U consti-.- tutes the auxiliary cathodeproper, the convex surface-of. which, coated with secondarily emissivematerial is=ar-'- ranged opposite a slit 11 of the anode; 4; sothatoscillation of the secondary electrons is ayoided,

The electron gun 3 may be of conventional construc-- tion and comprise,for example, a cathode; 12, behind. which a screen 13 is provided. Theintensity of the flow:

of electrons is governed by the plates 14 (gr) whereas the.concentrating plates 15 may be connected to the cathode 12. Theacceleration electrode 16 (g2) has a narrow slit 22. In this case theanode 4 is made of copper plated nickel and is welded to two studs,which are taken directly through the tube bottom to the outside.However, as an alternative, a larger number of studs may be arranged ina circle and connected to the anode 4. These studs also support thescreens 5, 6 and 7. The anode 4 is arranged between two mica centeringmembers 17 and 1S and is blackened 0n the outer side to improve thermalirradiation.

Fig. 3 shows the connections of the various inlets to variouselectrodes.

The mica member 17 has two apertures 19, having a diameter of 3 mms. toallow the cesium vapour to pass; the apertures are indicated by clashesin Fig. 2. Opposite the slit 11 of the anode 4 is provided a narrow slit20 in the two mica centering members 17 and 18, in order to reduceelectrostatic leakage and high-frequency losses.

At the top inside the tube a barium getter holder 21 is secured to theclosing plate 8.

In a dynatron circuit-arrangement comprising a tube, the cathode 12 ofwhich has a sprayed surface of 0.75 mm. in width and 10 mms. in length avery favourable effect is obtained. The slit 22 of the acceleratinganode 16 is 0.8 mm. The slit 11 has a width which is smaller than theWidth of the cathode 12 or equal thereto, i. e.

0.7 mm. and the width of the auxiliary cathode 9 facing the slit 11 is300 ,U. and the distance between the anode 4 a half times to twice thewidth of the slit 11, i. e. 1.4.

mms. The distance between the auxiliary cathode 9 and the slit 11 is 300n and the distance between the anode 4 and the accelerating electrode 16is 0.5 mm.

It was found that these dimensions of the tube could provide an outputof 0.53 watt at 200 mc./s. 0.35 watt at 300 to 500 mc./s. 0.10 watt at800 mc./s.

A construction according to the invention has an additional, importantadvantage in that these results were obtained without usingexceptionally high voltages, i. e. 250- v. at the anode 4, v. at theaccelerating electrode 16 and about 40 v. at the auxiliary cathode 9.

This auxiliary cathode 9 is formed by a. U--

little from that of conventional small-sized tubes, the

sameiadvantages and results are found to be obtainable as those of veryspecial constructions, such as light-house tubes and the like, which,however, must be driven by high voltages (about 1000 v.).

What I claim is:

1. An electric discharge device adapted for operation as a dynatronoscillator at very high frequencies, comprising an envelope including abottom portion, an electron gun for producing a ribbon-shaped beamdisposed in said envelope, a U-shaped auxiliary cathode in said envelopehaving a secondaryelectron-emissive surface on its base facing :saidelectron gun, a pin extending through the bottom portion of saidenvelope and secured in the envelope between the limbs of the U-shapedcathode for supporting said U-shaped cathode in its operative position,a cylindrical anode having an aperture for passage of the ribbon-shapedbeam coaxially surrounding said pin and said U-shaped cathode forcollecting the secondporting said cylindrical anode, a cylindricalscreen external to said envelope surrounding said pin and secured to andsupported by said studs, and a Lecher system ex ternal to said envelopefor transferring energy from said device to an external circuit, saidLecher system including a central conductor aligned with said pin, saidLecher system further including a cylindrical conductor surrounding saidcentral conductor and aligned with said cylindrical screen.

2. Anelectric discharge device as claimed in claim 1 in which a furthercylindrical screen aligned with said cylindrical anode is diSPOsedbetween said anode and the bottom portion of said envelope, said furtherscreen being secured to and supported by said connecting studs.

References Cited in the file of this patent UNITED STATES PATENTS2,513,3 1 ephe d 4, 1 50

